Deep drawing means are publicly known as means for forming cup-shaped containers, for example, from sheet metal. FIG. 4 is a partially cutaway perspective view of a typical process for forming cup-shaped containers using a press mold. In FIG. 4, numeral 101 refers to a punch formed into a cylindrical shape, for example, and vertically movably fitted to a press ram. Numeral 102 refers to a die formed into a hollow disc shape or a hollow cylindrical shape and fitted to a press table in a coaxial manner with respect to the punch 101. Numeral 103 refers to a blank holding pad formed into a hollow disc shape for pressing and releasing a work piece 104 onto and from a die 102 before and after the actuation of a punch 101.
With the above arrangement, a disc-shaped work piece 104 having an initial diameter, D.sub.O, for example, is positioned on the die 102 and forced onto the die 102 with a pushing force, Q, with the blank holding pad 103. As the punch 101 is then forced onto the work piece 104 with a drawing force, P, the work piece 104 is deep drawn into a cup-shaped container having a flange diameter, D. In this way, a metal forming process involving radial drawing of the work piece flange part 104a is called deep drawing. Deep drawing is a useful metal forming process for forming products having small wall thicknesses, such as cup-shaped containers, without generating a large amount of cutting chips as generated in machine working.
FIG. 5 is a longitudinal sectional view illustrating examples of products formed with deep drawing; (a) being a bottomed hollow tubular product, (b) a hollow tubular one with a through hole on the bottom, and (c) a hollow tubular one. The cross-sectional shape of the product may be a quadrangular, hexagonal, or other shape, in addition to a circular shape. The cross-sectional shape and dimensions may be varied at different locations in the axial direction.